Guide vane for a turbomachine, guide vane cascade, and method for manufacturing a guide vane or a guide vane cascade

ABSTRACT

A guide vane for a turbomachine axially pivotably coupled to a radially outwardly disposed flow-limiting wall and to a radially inwardly disposed inner ring of the turbomachine; and a trailing edge gap being formed between an upper trailing edge of the guide vane and the flow-limiting wall and/or between a lower trailing edge of the guide vane and the inner ring; the upper trailing edge and/or the lower trailing edge of the guide vane having at least one air outlet opening for an air outflow for forming an air curtain for at least partially sealing the trailing edge gap in the area of the upper trailing edge and/or the lower trailing edge in the area of the lower trailing edge. Also, a guide vane cascade, as well as a method for manufacturing a guide vane or a guide vane cascade.

This claims the benefit of European Patent Application EP13161903.3,filed Apr. 2, 2013 and hereby incorporated by reference herein.

The present invention relates to a guide vane for a turbomachine, inparticular for a compressor or a turbine of an aircraft engine, theguide vane being axially pivotably coupled to a radially outwardlydisposed flow-limiting wall and to a radially inwardly disposed innerring of the turbomachine; and a trailing edge gap being formed betweenan upper trailing edge of the guide vane and the flow-limiting walland/or between a lower trailing edge of the guide vane and the innerring. The present invention also relates to a guide vane cascade, aswell as to a method for manufacturing a guide vane or a guide vanecascade.

BACKGROUND

Guide vanes of this type for turbomachines are already known from therelated art. The guide vanes are configured in a compressor or a turbineof the turbomachine, in particular a thermal gas turbine, in such a waythat they are fixed relative to a housing of the turbomachine. Theturbomachine also includes a plurality of rotating rotor blades that areassigned to at least one rotor and rotate relative to the fixed guidevanes, as well as the stationary housing. Moreover, the guide vanes arecoupled to a radially inwardly disposed, static inner ring. To enhancethe efficiency of the turbomachine, the guide vanes, which are fixedrelative to the rotor blades, can be displaceably, respectivelypivotably configured about a radial axis. What is generally referred toas a trailing edge gap is thereby produced in each case between theinner side of the housing and a radially outer, upper trailing edge ofthe guide vane, respectively between the inner ring and the radiallyinner, lower trailing edge of the guide vane. The size of the trailingedge gap is dependent on the angular position of the guide vane. Thegreater the dimensions of the trailing edge gap, the more negative theeffect thereof on the efficiency and the surge limit of theturbomachine. This arises, in particular, from the fact that thetrailing edges are circumflowed by the working medium of theturbomachine, in particular, by air.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide a guide vane or aguide cascade of the type mentioned at the outset that will ensure anenhanced efficiency of a turbomachine. It is a further object of thepresent invention to manufacture such a guide vane or such a guide vanecascade with geometrical accuracy and inexpensively.

The present invention provides a guide vane, by a guide vane cascade, aswell as by a method.

In the case of a guide vane according to the present invention for aturbomachine, in particular for a compressor or a turbine of an aircraftengine, the guide vane is axially pivotably coupled to a radiallyoutwardly disposed flow-limiting wall and to a radially inwardlydisposed inner ring of the turbomachine; a trailing edge gap beingformed between an upper trailing edge of the guide vane and theflow-limiting wall and/or between a lower trailing edge of the guidevane and the inner ring. The upper trailing edge and/or the lowertrailing edge of the guide vane have/has at least one air outlet openingfor an air outflow for forming an air curtain for at least partiallysealing the trailing edge gap in the area of the upper trailing edge,and/or the lower trailing edge in the area of the lower trailing edge.By forming the air curtain in the trailing-edge gaps to the radiallyouter flow-limiting wall, which, in particular, may be assigned to ahousing of the turbomachine and/or to the inner ring of theturbomachine, a sealing of the trailing-edge gap is achieved that leadsto an enhanced efficiency of the turbomachine. The trailing edge gap isno longer able to be circumflowed by air. The number and form of the airoutlet openings may be selected in such a way that the trailing edgegap(s) is/are sealed over the entire adjustment range(s) of the guidevanes.

In one advantageous embodiment of the guide vane according to thepresent invention, the air outlet opening communicates air-conductivelyvia at least one channel with at least one air inlet opening on a bladesurface of the guide vane. The air inlet opening may be configured onthe pressure side of the guide vane. As a result, a sufficient airvolume is always available for producing the air curtain to seal thetrailing edge gap. In this context, the expression “air” connotes anypossible usable gaseous working medium of the turbomachine.

Another advantageous embodiment of the guide vane according to thepresent invention provides that at least one localized thickened portionof the blade of the guide vane be formed in the area of the air inletopening prior to the manufacture of the air inlet opening. This makes itadvantageously possible to use virtually any position for the air inletopening on the blade. In particular, this allows an optimal aerodynamicpositioning of the air inlet opening.

Another advantageous embodiment of the guide vane according to thepresent invention provides that at least one air baffle be configured onthe blade in the area of the air inlet opening. This allows air currentsto be selectively directed into the air inlet opening.

Other advantageous embodiments of the guide vane according to thepresent invention provide for the air outlet opening to be funnel- orslit-shaped. However, other specific embodiments are also conceivable.The funnel-shaped form of the air outlet opening ensures that asufficient air volume is always available. The slit-shaped form of theair outlet opening may be used for exactly controlling the shape of thethereby forming wall of air. In particular, the longitudinal axes of aplurality of serially disposed air outlet openings may extendapproximately in parallel to the blade cross section of the guide vanes.This ensures that the appropriate wall of air is formed over the entirelower trailing edge.

The present invention also relates to a guide vane cascade of aturbomachine, in particular of a compressor or a turbine of an aircraftengine, including at least two guide vanes in accordance with thepresent invention. The form of such adjustable guide cascades accordingto the present invention ensures an enhanced efficiency of thecorresponding turbomachine.

The present invention also relates to a method for manufacturing a guidevane or a guide vane cascade, as described in the preceding; the guidevane or the guide vane cascade being manufactured using a generativeproduction process. The generative production process may be a selectivelaser melting process or a selective laser sintering process. Othergenerative manufacturing processes are also conceivable. By usinggenerative production processes, the guide vanes or the correspondingguide vane cascades may be manufactured with geometrical accuracy andinexpensively. However, it is self-evident that conventionalmanufacturing processes, such as casting processes, for example, may beused to produce the guide vanes according to the present invention orthe guide vane cascade according to the present invention.

Other features of the present invention are derived from the claims, theexemplary embodiment, as well as in light of the drawing. Theaforementioned features and combinations of features, as well as thefeatures and combinations of features mentioned in the exemplaryembodiments may be used not only in the particular stated combination,but also in other combinations or alone, without departing from thescope of the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS

The figures show:

FIG. 1 a schematic representation of a partial area of a guide vaneaccording to the present invention; and

FIG. 2 a schematically illustrated plan view of the inventive guidevane.

DETAILED DESCRIPTION

Guide vane 10 partially illustrated in FIG. 1 is axially pivotablycoupled by radially outwardly disposed end thereof to a flow-limitingwall 12. In the illustrated exemplary embodiment, wall 12 is a housing32 of an axial compressor of a turbomachine, in particular of anaircraft engine. It is discernible that guide vane 10 is configured on acorresponding inner side of flow-limiting housing wall 12. It is alsodiscernible that guide vane 10 features a leading edge 38 and a trailingedge 40, which, in a corresponding flow volume, are oriented in a flowdirection S of the turbomachine. Moreover, guide vane 10 is coupled to aradially inwardly disposed inner ring of the turbomachine. A trailingedge gap 16 is formed between an upper trailing edge 14 of guide vane 10and flow-limiting wall 12. This holds correspondingly for the lowertrailing edge of guide vane 10 and the inner ring of turbomachine. It isdiscernible that upper trailing edge 14 has a plurality of air outletopenings 18 for an air outflow for forming an air curtain 20 for sealingtrailing edge gap 16 in the area of upper trailing edge 14. Air outletopenings 18 are funnel-shaped. Moreover, the particular air outletopenings 18 each communicate air-conductively via a channel 22, which isformed within a blade 36 of guide vane 10, with an air inlet opening 26on a surface 24 of blade 36. It may also be appreciated that air inletopenings 26 are formed on pressure side D of guide vanes 10. Alsoillustrated is an optional baffle 25 which is configured on the blade inthe area of the inlet openings 26 to allow air currents to beselectively directed to the air inlet openings 26.

Guide vane 10 is pivotably mounted about an axis of rotation 34 inhousing 32. A pivot pin 28 extends into a corresponding recess 30 ofhousing 32 and is pivotably mounted therein.

FIG. 2 shows a schematically illustrated view of pivotable guide vane 10in accordance with FIG. 1. It is discernible that air outlet openings 18are configured on upper trailing edge 14. The air inlet openings areformed on blade surface 24 on the pressure side of guide vane 10. Guidevane 10 is pivotably mounted about axis of rotation 34.

Guide vane 10 shown in FIGS. 1 and 2 may be coupled to a plurality offurther guide vanes to form an adjustable guide cascade. Besides theoption of manufacturing the guide cascade or guide vane 10 usingconventional casting processes, a generative production process, inparticular a selective laser melting or selective laser sinteringprocess, may also be used to manufacture guide vanes 10 or acorresponding guide vane cascade composed of a plurality of guide vanes10. In this context, a two-stage process is repeatedly carried out; auniform powder bed of a metal powder being prepared in a first stage ofthe two-stage process. The metal powder of the powder bed is selectivelyfused on and consolidated in a second stage, on the basis of layersgenerated by a three-dimensional CAD model. By repeatedly executing thistwo-stage process, guide vane 10 to be manufactured or the correspondingguide vane cascade is built up in layers and, thus, successively. Themetal powder prepared in the first step is composed, in particular, of anickel- or titanium-based alloy.

What is claimed is:
 1. A guide vane for a turbomachine comprising: anupper trailing edge and a lower trailing edge, the guide vane beingaxially pivotably coupled to a radially outwardly disposed flow-limitingwall and to a radially inwardly disposed inner ring of the turbomachine,a trailing edge gap being formed between the upper trailing edge of theguide vane and the flow-limiting wall or between the lower trailing edgeof the guide vane and the inner ring, wherein the upper trailing edge orthe lower trailing edge of the guide vane has at least one air outletopening for an air outflow for forming an air curtain for at leastpartially sealing the trailing edge gap in the area of the uppertrailing edge or the trailing edge gap in the area of the lower trailingedge; wherein the guide vane has a blade surface, the air outlet openingcommunicating air-conductively via at least one channel with at leastone air inlet opening on the blade surface; and wherein the air inletopening is configured on a pressure side of the guide vane.
 2. The guidevane as recited in claim 1 wherein at least one localized thickenedportion of the guide vane is formed in the area of the air inlet openingprior to the manufacture of the air inlet opening.
 3. The guide vane asrecited in claim 1 further comprising at least one air baffle in thearea of the air inlet opening.
 4. The guide vane as recited in claim 1wherein the air outlet opening is configured to be funnel- orslit-shaped.
 5. A compressor or turbine of an aircraft engine comprisingthe guide vane as recited in claim
 1. 6. A guide vane cascade of aturbomachine comprising at least two guide vanes as recited in claim 1.7. A compressor or turbine of an aircraft engine comprising the guidevane cascade as recited in claim
 6. 8. A method for manufacturing aguide vane cascade as recited in claim 6 wherein the at least two guidevanes are manufactured using a generative production process.
 9. Amethod for manufacturing a guide vane as recited in claim 1 wherein theguide vane is manufactured using a generative production process. 10.The method as recited in claim 9 wherein the generative productionprocess is a selective laser melting process or a selective lasersintering process.